In many fields of the metalworking industry, welding is carried out by the TIG Process (tungsten,inert-gas process). The tungsten electrodes used in this process as the carrier of the welding arc are doped with oxidic additives generally thorium oxide, in order to improve their ignition properties.
The startability of the electrodes presently in use decreases substantially as the number of starts increases. Contact-free ignition is, in most cases, no longer possible after only about ten restarts with merely brief disconnection of the current, about 10 seconds after the termination of the flow of the inert gas. Due to the short lives of these electrodes the cost of the finished products is greatly increased.